@fdodelap. Welcome to MayoClinicConnect! We’re a community of volunteers, who through our own health journeys, try to help others through theirs. We’re not doctors so we cannot diagnose or prescribe. But we try to help from experiences and information. I found some information about the rare possibility of myocarditis.
https://www.healthychildren.org/English/tips-tools/ask-the-pediatrician/Pages/Does-the-COVID-19-vaccine-cause-myocarditis-in-teens-and-young-people.aspx
https://www.aappublications.org/news/2021/06/04/covid-vaccine-myocarditis-case-reports-060421
These sources are from pediatricians.

What does your child’s doctor say about the possibility of myocarditis?
Tell us a little more about your son. Does he have a health condition that you are concerned about?